JP2003109768A - Light emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emitting element with high light emitting efficacy high brightness and excellent color purity. SOLUTION: The light emitting element emits light by electric energy with a light emitting matter existing between a positive electrode and a negative electrode, and contains organic materials and triplet light emitting materials with sublimation property and molecular weight of 600 or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device capable of converting electric energy into light, such as a display device, a flat panel display, a backlight, a lighting, an interior, a sign, a signboard, an electrophotographic machine and an optical signal generator. The present invention relates to a light emitting element that can be used in the field of.

[0002]

2. Description of the Related Art In recent years, active research has been carried out on organic laminated thin-film light emitting devices in which electrons injected from a cathode and holes injected from an anode emit light when recombined in an organic phosphor sandwiched between both electrodes. ing. This element has attracted attention because it is thin, has high-luminance light emission under a low driving voltage, and has multicolor light emission by selecting a fluorescent material.

This work was carried out by Kodak Corp. W. Tan
Since g. et al. showed that the organic laminated thin film light emitting device emits light with high brightness (Appl. Phys. Lett. 51 (1
2) 21, p. 913, 1987), many research institutes are investigating. A typical structure of an organic laminated thin film light emitting device presented by a Kodak research group is a diamine compound having a hole-transporting property on a tin indium oxide (ITO) glass substrate and tris (8-quinolinolato) which is a light emitting layer.
Aluminum and Mg: Ag are sequentially provided as a cathode, and the drive voltage of about 10 V is 1000 cd /
A green light emission of m ² was possible. Some of the current organic laminated thin-film light-emitting elements have different configurations such as an element having an electron transport layer in addition to the above-mentioned element components, but basically follow the configuration of Kodak Corporation.

As the light emitting material constituting the above light emitting layer,
A host material alone or a host material doped with a dopant material is used. It is required that the light emitting material has three primary colors of red, green and blue for full color display.

Conventionally, a fluorescent (singlet emission) material has been generally used as a light emitting material. However, due to a difference in spin multiplicity when electrons and holes are recombined to excite molecules. , Singlet excitons 25%, triplet excitons 75%
It has been attempted to use phosphorescent (triplet emission) materials in order to improve the emission efficiency, and the group at Princeton University emits light more than conventional fluorescent materials. It shows that the efficiency is significantly higher (Appl. Phys. Lett. 75, 4
(1999)).

[0006]

However, the light emitting device manufactured by the above-mentioned conventional technique is not sufficiently durable, and the phosphorescent material itself is improved, and the hole transport material, host material, electron transport material, etc. Improvement is desired.

[0007] Therefore, an object of the present invention is to solve the problems of the prior art and to provide a light emitting device having high luminous efficiency, high color purity and excellent durability.

[0008]

That is, the present invention is an element in which a light-emitting substance is present between an anode and a cathode, and which emits light by electric energy, has sublimability, and has a molecular weight of 6
It is a light emitting device comprising an organic material of 00 or more and a triplet light emitting material.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the anode is tin oxide, indium oxide, IT if transparent to take out light.
Conductive metal oxides such as O, metals such as gold, silver and chromium, inorganic conductive substances such as copper iodide and copper sulfide, and conductive polymers such as polythiophene, polypyrrole and polyaniline are not particularly limited. It is particularly preferable to use ITO glass or Nesa glass. The resistance of the electrode is not limited as long as it can supply a sufficient current for light emission of the light emitting element, but is preferably low resistance from the viewpoint of power consumption of the light emitting element. For example, if ITO glass of 300Ω / □ or less functions as an element electrode, it is now possible to supply a substrate of about 10Ω / □.
It is particularly preferable to use a low resistance product.

When the ITO glass is used, the thickness of the ITO film can be arbitrarily selected according to the resistance value, but it is usually preferable to set it to be 100 to 300 nm. Further, the thickness of the glass substrate may be any thickness sufficient to maintain the mechanical strength, and specifically, it is preferably 0.5 mm or more. As for the material of the glass substrate, non-alkali glass is preferable because it is preferable that the amount of ions eluted from the glass is small, but soda lime glass having a barrier coat such as commercially available SiO ₂ can also be used. Also, a plastic substrate may be used.

The ITO film forming method is not particularly limited, such as an electron beam method, a sputtering method and a chemical reaction method.

In the present invention, the cathode is not particularly limited as long as it is made of a substance capable of efficiently injecting electrons into the light emitting substance, and specifically, platinum, gold, silver, copper, iron, tin, zinc, aluminum, Examples thereof include indium, chromium, lithium, cesium, sodium, potassium, calcium and magnesium. In particular, lithium, cesium, sodium, potassium, calcium, magnesium or alloys containing these low work function metals are effective for increasing electron injection efficiency and improving device characteristics.

However, since these low work function metals are often unstable in the atmosphere, for example, trace amounts of lithium, cesium, and magnesium (1 nm or less in a vacuum evaporation film thickness meter display) are present in the organic layer. It is preferable to use a highly stable electrode doped with, but it is also possible to use an inorganic salt such as lithium fluoride, and it is not particularly limited thereto. Furthermore, platinum for electrode protection,
Metals such as gold, silver, copper, iron, tin, aluminum and indium, or alloys using these metals, and silica,
Preferred examples include laminating inorganic materials such as titania and silicon nitride, polyvinyl alcohol, vinyl chloride, and hydrocarbon polymers.

The method for producing the above-mentioned cathode is not particularly limited as long as conduction can be established, such as a resistance heating method, an electron beam method, a sputtering method, an ion plating method and a coating method.

In the present invention, the luminescent substance refers to a compound that is involved in light emission, which corresponds to both a substance which emits light by itself and a substance which assists the light emission. Specifically, it corresponds to a light emitting material, a hole transporting material, an electron transporting material, a hole blocking material and the like.

The light-emitting device of the present invention may have various constitutions other than the anode and the cathode, for example, 1) hole transport layer /
Light-emitting layer, 2) hole-transporting layer / light-emitting layer / electron-transporting layer, 3) light-emitting layer / electron-transporting layer, 4) hole-transporting layer / light-emitting layer / hole-blocking layer, 5) hole-transporting layer / light-emitting layer / Hole blocking layer / electron transporting layer, 6) light emitting layer / hole blocking layer / electron transporting layer, and 7)
Examples include the case of a light emitting layer.

In the present invention, the luminescent material has a molecular weight of 60.
It is necessary to include zero or more organic materials and triplet light emitting materials,
Since the triplet light emitting material often plays a role of emitting light by itself, it is particularly preferably contained in the light emitting material forming the light emitting layer, and particularly preferably used as a dopant material described later.

A triplet light emitting material has higher luminous efficiency than a conventional singlet light emitting material, and a light emitting device using the triplet light emitting material is desired to have a wider range of applications and higher durability.

In order to obtain light emission efficiently, it is necessary to cause the recombination of electrons and holes in the light emitting layer. However, of the recombination energies, those not used for light emission become heat.
The light emitting layer is most susceptible to damage. Therefore, the molecular weight is 6
Organic materials of 00 or more have excellent heat resistance, and are therefore preferably used in the light emitting layer. The molecular weight is more preferably 803 or more, further preferably 900 or more.

Regarding the molecular weight of the triplet light emitting material, since it is contained only in a trace amount in the film, its influence on its durability is slight.

The light emitting device is preferably manufactured by laminating each material, but since the ITO substrate which is an anode is generally used as the substrate, the hole transport layer is most likely to be affected by the base. Therefore, an organic material with a molecular weight of 600 or more
Since it is excellent in thin film stability, it is preferably used in the hole transport layer.

The metal layer as the cathode is generally formed last, but the vapor deposition method is used for the film formation, and the radiant heat at that time adversely affects the organic layer already laminated. Cheap. Therefore, an organic material having a molecular weight of 600 or more is preferably used in the electron transport layer because it has excellent heat resistance.

Since the triplet light emitting material emits light by a mechanism different from that of the conventional fluorescent material (singlet light emission),
The material group used together with the conventional fluorescent material is not always applicable to the combination with the triplet light emitting material as it is. In many cases, it cannot be applied especially when used in the same layer. Therefore, when considering a combination with a triplet material, compounds represented by the following general formulas (1) to (5) can be given as preferable examples as the organic material having a molecular weight of 600 or more.

[0024]

[Chemical 6]

(Here, R ^{1 to} R ^{10, which} may be the same or different, are each hydrogen, an alkyl group, an aryl group,
It is selected from an alkoxy group and a condensed aromatic hydrocarbon ring structure formed between adjacent alkoxy groups. X ¹ is selected from a single bond, an alkyl chain, a cycloalkyl chain, an alkylene chain, an aryl chain, a heterocyclic chain, a silyl chain, an ether chain and a thioether chain, alone or in combination. n represents a natural number of 2 or more. )

[0026]

[Chemical 7]

(Here, R ¹¹ is selected from hydrogen, alkyl, and aryl groups. N represents a natural number of 4 or more.)

[0028]

[Chemical 8]

(Where R¹²~ R^{twenty one}Are the same
May be different, hydrogen, an alkyl group, an aryl group,
Condensation formed between an alkoxy group and an adjacent substituent
It is selected from aromatic hydrocarbon ring structures. Also, R¹⁶-R¹⁷
The spaces may be connected. X ²Is a single bond, alkyl
Chain, cycloalkyl chain, alkylene chain, aryl chain, compound
Any of elementary chain, silyl chain, ether chain, thioether chain
Selected from them alone or in combination. n
Represents a natural number of 2 or more. )

[0030]

[Chemical 9]

(Where R^{twenty two}~ R²⁹Are the same
May be different, hydrogen, an alkyl group, an aryl group,
Selected from alkoxy groups. However, R^{twenty two}~ R²⁹Out of 1
One is X ³Used to combine with. X³Is a single bond, alkyl
Chain, cycloalkyl chain, alkylene chain, aryl chain, compound
Any of elementary chain, silyl chain, ether chain, thioether chain
Selected from them alone or in combination. n
Represents a natural number of 2 or more. )

[0032]

[Chemical 10]

(Wherein R ³⁰ represents a substituent which is modified at any position and is selected from hydrogen, an alkyl group, an aryl group and an alkoxy group. X ⁴ is a single bond, an alkyl chain, a cycloalkyl chain or an alkylene. Chain, aryl chain, heterocyclic chain,
It is selected from a silyl chain, an ether chain and a thioether chain, alone or in combination. Y is selected from oxygen and nitrogen, and in the case of nitrogen, hydrogen, an alkyl group or an aryl group is modified. n represents a natural number of 2 or more. In the description of these substituents, the alkyl group represents a saturated aliphatic hydrocarbon group such as a methyl group and an ethyl group, which may be unsubstituted or substituted. The aryl group represents, for example, an aromatic hydrocarbon group such as a phenyl group, a naphthyl group, a biphenyl group and a fluorenyl group, which may be unsubstituted or substituted. The alkoxy group refers to an aliphatic hydrocarbon group via an ether bond such as a methoxy group, which may be unsubstituted or substituted. In the light of the effect of the present invention, these substituents are the hydrogens on each compound and the substituents having equivalent properties.

X ^{1 to} X ⁵ are connecting chains for connection, and by connecting with the connecting chains, it is possible to impart heat resistance and thin film forming ability which cannot be obtained by conventional single compounds. Further, durability as an element can be imparted, and a useful light emitting element can be obtained. Examples of the bonding chain include a single bond, an alkyl chain, an alkylene chain, a cycloalkyl chain, an aryl chain, a heterocyclic chain, a silyl chain, an ether chain, or a thioether chain, but thermal stability and electron and / or hole transport As a preferable bonding chain for enhancing the activity, a single bond, an alkylene chain, an aryl chain and a heterocyclic chain can be mentioned. Furthermore, a rigid and bulky structure is desirable for further heat resistance and thin film formation,
Specifically, a binding chain composed of a plurality of aryl chains is more preferable.

General formula (1) having a molecular weight of 600 or more
Specific examples of the organic material compound represented by (5) are shown below, but the invention is not limited thereto.

[0036]

[Chemical 11]

[0037]

[Chemical 12]

Even if the luminescent substance is composed only of the organic material represented by the general formulas (1) to (5) having a molecular weight of 600 or more and the triplet material, it is combined with various other conventionally used materials. It doesn't matter.

The organic material having a molecular weight of 600 or more according to the present invention has sublimability. The sublimability used here does not mean that a solid is vaporized without passing through a liquid, but is used in a broad sense that it volatilizes without decomposition when heated in a vacuum and a thin film can be formed. ing. The light emitting device of the present invention preferably has a laminated structure, but if it is an organic compound having a sublimation property, the laminated structure can be easily formed by a dry process such as a vacuum deposition method. Also, when forming a doping layer in the light emitting layer, a doping layer excellent in controllability can be formed by using a co-evaporation method with a host material or a method of pre-mixing with a host material and then performing vapor deposition at the same time. Furthermore, it is necessary to obtain desired patterned light emission when forming a display that uses a matrix or segment system, but an organic compound having a sublimation property can be easily patterned by patterning by a dry process. .

The hole-transporting layer is a layer for injecting holes from the anode and for further transporting holes, and the material used for the hole-transporting layer (hereinafter referred to as the hole-transporting material) is either alone or different. It may be laminated or mixed with the hole transport material.

The light emitting layer is a layer which actually controls light emission by accumulating the electric energy injected from the anode and the cathode as energy for light emission. The material used for the light emitting layer (hereinafter referred to as the light emitting material) is preferably a compound having fluorescence or phosphorescence.

Further, when light emission is obtained by using a light emitting material, energy is accumulated, a case where a single light emitting material is used for actual light emission and energy transition are utilized to separate functions and combine a plurality of light emitting materials. It may be used. In the latter case, it is classified into a light emitting material (hereinafter, referred to as a host material) that is responsible for storing electric energy and a light emitting material (hereinafter, a dopant material) that receives the stored energy and actually controls light emission. Such a method of functional separation is called a doping method, and by this method, high efficiency, high color purity,
A highly durable light emitting element can be obtained.

These light-emitting materials can be used alone or in combination of two or more kinds, and the light-emitting layer can be used in multiple layers.

In the doping method, the dopant material may be contained in the entire host material, may be partially contained, or may be contained in any part. May be laminated. The host materials may be used alone or in combination of two or more.

As the dopant material of the light emitting material, only one of the above triplet light emitting materials may be used, or a plurality of triplet light emitting materials may be mixed and used. Furthermore, one or more kinds of known singlet dopant materials and triplet light emitting materials may be used. You may mix and use with a light emitting material.

The above-mentioned electron transport layer is a layer for injecting electrons from the cathode and further for transporting electrons, and the material used for the electron transport layer (hereinafter referred to as electron transport material) is a single or different electron transport material. They may be laminated or mixed and used.

The hole blocking layer is a layer which efficiently blocks holes from the anode from flowing to the cathode side without recombination.
Material used for hole blocking layer (hereinafter referred to as hole blocking material)
These may be used alone or in a laminate or a mixture with different hole blocking materials.

The hole transporting material is a material that efficiently transports holes from the anode between the electrodes to which an electric field is applied, has a high hole injection efficiency, and efficiently transports the injected holes. Is preferred. For that purpose, the ionization potential is small and the hole mobility is large,
Further, it is required to be made of a material that is excellent in stability and in which impurities that become traps are hard to be generated during manufacturing and use. The organic material having a molecular weight of 600 or more according to the present invention can be mentioned as a material satisfying such a condition. Among them, the organic materials represented by the general formulas (1) to (3) are particularly preferable. In addition, N, N'-diphenyl-N,
N'-di (3-methylphenyl) -4,4'-diphenyl-1,1'-diamine, N, N'-dinaphthyl-N,
N'-diphenyl-4,4'-diphenyl-1,1'-
Triphenylamines such as diamine, carbazole derivatives such as bis (N-allylcarbazole) or bis (N-alkylcarbazole) s, pyrazoline derivatives,
Stilbene compounds, hydrazone compounds, heterocyclic compounds typified by oxadiazole derivatives and phthalocyanine derivatives, porphyrin derivatives, and in polymer systems, polycarbonates or styrene derivatives having the above monomer in the side chain, polyvinylcarbazole, polysilane and the like are preferable. For example, forming a thin film necessary for manufacturing a light emitting device,
The compound is not particularly limited as long as it is a compound capable of injecting holes from the anode and further transporting holes.

The host material has a molecular weight of 60 according to the present invention.
There are 0 or more organic materials, and among them, the organic materials represented by the general formulas (1) to (5) are particularly preferred. In addition, although not particularly limited, anthracene, which has been known as a luminous body for a long time,
Fused ring derivatives such as phenanthrene, pyrene, perylene, chrysene, metal complexes of quinolinol derivatives such as tris (8-quinolinolato) aluminum, benzoxazole derivatives, stilbene derivatives, benzthiazole derivatives, thiadiazole derivatives, thiophene derivatives,
Tetraphenyl butadiene derivative, cyclopentadiene derivative, oxadiazole derivative, bisstyryl derivative such as bisstyrylanthracene derivative and distyrylbenzene derivative, carbazole derivative such as bis (N-carbazolyl) biphenyl, triazole derivative, phenanthroline derivative, triphenylamine derivative , A metal complex combining a quinolinol derivative and a different ligand,
Oxadiazole derivative metal complex, benzazole derivative metal complex, coumarin derivative, pyrrolopyridine derivative,
For the perinone derivative, the thiadiazolopyridine derivative, and the polymer system, a polyphenylene vinylene derivative, a polyparaphenylene derivative, and a polythiophene derivative can be used.

Specific examples of the triplet light emitting material include tris (2-phenylpyridyl) iridium complex, tris {2- (2-thiophenyl) pyridyl} iridium complex, and tris {2- (2-benzothiophenyl) pyridyl. } Iridium complex, tris (2-phenylbenzothiazole) iridium complex, tris (2-phenylbenzoxazole) iridium complex, trisbenzoquinolineiridium complex, bis (2-phenylpyridyl) (acetylacetonato) iridium complex, bis {2 -(2-
Thiophenyl) pyridyl} iridium complex, bis {2-
(2-benzothiophenyl) pyridyl} (acetylacetonato) iridium complex, bis (2-phenylbenzothiazole) (acetylacetonato) iridium complex, bis (2-phenylbenzoxazole) (acetylacetonato) iridium complex, bis Benzoquinoline (acetylacetonato) iridium complex, bis {2-
(2,4-Difluorophenyl) pyridyl} (acetylacetonato) iridium complex, tetraethylporphyrin platinum complex, {tris (cenoyltrifluoroacetone) mono (1,10-phenanthroline)} europium complex, {tris (cenoyltrifluoroacetone) ) Mono (4,7-diphenyl-1,10-phenanthroline)} europium complex, {tris (1,3-diphenyl-1,3-propanedione) mono (1,10-phenanthroline)} europium complex, trisacetylacetoneterbium Examples thereof include, but are not limited to, complexes. Among the phosphorescent (triplet emission) materials, an iridium complex or a platinum complex is preferably used because it has good emission characteristics.

The known singlet dopant material is not particularly limited, but specifically, conventionally known phenanthrene, anthracene, pyrene, tetracene, pentacene, perylene, naphthopyrene, dibenzopyrene, rubrene. Such as condensed ring derivatives, benzoxazole derivatives, benzthiazole derivatives, benzimidazole derivatives, benztriazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, imidazole derivatives, thiadiazole derivatives, triazole derivatives, pyrazoline derivatives, thiophene derivatives, tetraphenyl Butadiene derivatives, cyclopentadiene derivatives, bisstyryl anthracene derivatives, bisstyryl derivatives such as distyrylbenzene derivatives, pyrromethene derivatives and Metal complex, furan derivative, benzofuran derivative, phenylisobenzofuran, dimesitylisobenzofuran, di (2-methylphenyl) isobenzofuran, di (2-trifluoromethylphenyl) isobenzofuran, isobenzofuran derivative such as phenylisobenzofuran, Dibenzofuran derivative, 7-dialkylaminocoumarin derivative, 7-piperidinocoumarin derivative, 7-hydroxycoumarin derivative, 7-methoxycoumarin derivative, 7-acetoxycoumarin derivative, 3-benzthiazolylcoumarin derivative, 3-benzimidazolylcoumarin Derivative, coumarin derivative such as 3-benzoxazolyl coumarin derivative, dicyanomethylenepyran derivative, dicyanomethylenethiopyran derivative, polymethine derivative, cyanine derivative, oxoben Anthracene derivatives, xanthene derivatives, rhodamine derivatives, fluorescein derivatives, pyrylium derivatives, carbostyril derivatives, acridine derivatives, oxazine derivatives, polyphenylene oxide derivatives, quinacridone derivatives, quinazoline derivatives, pyrrolopyridine derivatives, furopyridine derivatives,
1,2,5-thiadiazolopylene derivative, perinone derivative, pyrrolopyrrole derivative, squarylium derivative, violanthrone derivative, phenazine derivative, acridone derivative, diazaflavin derivative and the like can be used.

The electron transport material needs to efficiently transport the electrons from the cathode between the electrodes to which an electric field is applied, and the electron injection efficiency is high, and it is preferable that the injected electrons are efficiently transported. For that purpose, the electron affinity is large, the electron mobility is large, and the stability is excellent.
It is required that impurities that become traps are materials that do not easily generate during manufacturing and use. Examples of the electron-transporting material satisfying such conditions include organic materials having a molecular weight of 600 or more according to the present invention. Among them, the organic materials represented by the general formulas (4) and (5) are particularly preferable.
In addition, quinolinol derivative metal complex represented by tris (8-quinolinolato) aluminum, tropolone metal complex, flavonol metal complex, perylene derivative, perinone derivative, naphthalene, coumarin derivative, oxadiazole derivative, aldazine derivative, bisstyryl derivative, Examples thereof include pyrazine derivatives and phenanthroline derivatives, but are not particularly limited.

In consideration of the transport balance of holes and electrons, the hole blocking material needs to be able to efficiently block holes from the anode from flowing to the cathode side without recombining. It is preferable that the efficiency is low. For that purpose, it is required that the material has a large ionization potential, a small hole mobility, an excellent stability, and an impurity that becomes a trap is hard to be generated at the time of production and use.
As the hole blocking material satisfying such a condition, the above electron transporting material can be used, but a material having a low electron transporting ability may be used. These hole blocking materials may be used alone or in a laminated or mixed with different hole blocking materials.

In the present invention, each layer constituting the light emitting substance is formed by vacuum vapor deposition, and among them, resistance heating method, electron beam method, sputtering method and molecular lamination method are preferable.
The thickness of each layer cannot be limited because it depends on the resistance value, but it is usually preferably 1 to 1000 nm.

In the present invention, the electric energy mainly means a direct current, but it is also possible to use a pulse current or an alternating current. The current value and voltage value are not particularly limited,
Considering the power consumption and life of the light emitting device, the maximum brightness should be obtained with the lowest possible energy.

The light emitting device of the present invention comprises a matrix and / or
Alternatively, the display is preferably a segment type display.

The matrix means a matrix in which pixels for display are arranged, and a character or an image is displayed by a set of pixels. The shape and size of the pixel depend on the application. For example, a quadrangular pixel with a side of 300 μm or less is usually used for displaying images and characters on a personal computer, a monitor, a television, and in the case of a large display such as a display panel, a pixel with a side of mm is used. . In the case of monochrome display, pixels of the same color may be arranged, but in the case of color display, red, green, and blue pixels are displayed side by side. In this case, there are typically a delta type and a stripe type. The driving method of this matrix may be either a line-sequential driving method or an active matrix. The line-sequential driving has an advantage that the structure is simple, but in consideration of the operation characteristics, the active matrix may be superior in some cases. Therefore, it is necessary to use the active matrix depending on the application.

In the segment system, a pattern is formed so as to display predetermined information, and a predetermined area is made to emit light. For example, a time and temperature display on a digital clock or a thermometer, an operation state display of an audio device or an electromagnetic cooker, a panel display of an automobile, and the like can be given. The matrix display and the segment display may coexist in the same panel.

[0059]

The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the examples, the film thickness is the crystal oscillation type film thickness monitor display value.

Example 1 A glass substrate (manufactured by Asahi Glass Co., Ltd., 15 Ω / □, electron beam method product) on which an ITO transparent conductive film was deposited to a thickness of 150 nm was cut into 30 × 40 mm and etched. The obtained substrate is "Semicoclin 56" (manufactured by Furuuchi Chemical Co., Ltd.)
And ultrasonic cleaning with ultrapure water for 15 minutes and dried. This substrate was subjected to UV-ozone treatment for 1 hour immediately before producing a light emitting device, placed in a vacuum vapor deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ⁻⁵ Pa or less. According to the resistance heating method, first, 4,4'-bis (N
60 nm of-(1-naphthyl) -N-phenylamino) biphenyl (αNPD: molecular weight 589) was deposited. Next, 2,2'-bis (4-
(N, N'-diphenylamino) phenyl) spiro-
9,9'-bifluorene (molecular weight: 803) was used as a dopant material using a tris (2-phenylpyridyl) iridium complex (Ir (ppy) ₃ : molecular weight 655) to obtain a dopant of 8 wt% and a thickness of 30 nm. It was co-deposited. Next, 10 nm of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BTCPN: molecular weight 360) was vapor-deposited as a hole blocking material. Next, as an electron transporting material, tris (8-quinolinol) was used.
Aluminum complex (molecular weight 459) was evaporated to a thickness of 50 nm. Next, after doping the organic layer with 0.5 nm of lithium, aluminum was vapor-deposited with 200 nm to serve as a cathode, and a 5 × 5 mm square light emitting device was produced. An emission spectrum similar to the phosphorescence spectrum of the dopant material was observed from this light-emitting device, and high-luminance green emission with favorable color purity was obtained.

In addition, the above light emitting device was
Pulse drive (Duty ratio 1/60, pulse current value 6)
0 mA), an emission spectrum similar to the phosphorescence spectrum of the dopant material was observed, and high-brightness green emission with good color purity was confirmed.

Further, when the durability was evaluated by driving with a direct current of 20 mA / square centimeter, high-brightness green light emission with good color purity was obtained even after 100 hours.

Comparative Example 1 A light emitting device was produced in exactly the same manner as in Example 1 except that 4,4′-bis (N-carbazolyl) biphenyl (CBP: molecular weight 484) was used as the host material of the light emitting material. An emission spectrum similar to the phosphorescence spectrum of the dopant material was observed from this light-emitting element, and high-intensity green light emission with favorable color purity was obtained. The durability was evaluated at a DC drive of 20 mA / square centimeter for 100 hours. After that, a remarkable decrease in brightness was observed.

Example 2 As a host material of a light emitting material, 2,2'-bis {5- (4
A light emitting device was produced in the same manner as in Example 1 except that -t-butylphenyl) 1,3,4-oxadiazol-2-yl} spiro-9,9'-bifluorene (molecular weight: 717) was used. .

From this light emitting device, an emission spectrum similar to the phosphorescence spectrum of the dopant material was observed, and high-brightness green light emission with good color purity was obtained. Furthermore, 20mA
When the durability was evaluated by driving with a direct current of / cm2, a high-brightness green light emission with good color purity was obtained even after 100 hours.

Example 3 4,4′-bis (N-carbazolyl) biphenyl (CBP: molecular weight 484) was used as the host material of the light emitting material, and N, N′-bis (4-diphenylamino) was used as the hole transport material. A light emitting device was produced in exactly the same manner as in Example 1 except that -4-biphenyl) -N, N'-diphenylbenzidine (molecular weight 975) was used. An emission spectrum similar to the phosphorescence spectrum of the dopant material was observed from this light-emitting element, and high-intensity green light emission with favorable color purity was obtained. The durability was evaluated at a DC drive of 20 mA / square centimeter for 100 hours. Even after that, high-brightness green light emission with good color purity was obtained.

Example 4 A light emitting device was produced in the same manner as in Example 3 except that ethylcarbazole tetramer linked at the 3 and 6 positions was used as a hole transport material. An emission spectrum similar to the phosphorescence spectrum of the dopant material was observed from this light emitting device, and high-intensity green light emission with good color purity was obtained.
When the durability was evaluated by direct-current driving of a square centimeter, high-intensity green light emission with good color purity was obtained even after 100 hours.

Example 5 4,4′-bis (N-carbazolyl) biphenyl (CBP: molecular weight 484) was used as the host material of the light emitting material, and 2,2 ′, 7,7′-tetrakis was used as the hole blocking material. A light emitting device was produced in exactly the same manner as in Example 1 except that (2-phenanthrolyl) spiro-9,9′-bifluorene (molecular weight 1029) was used. An emission spectrum similar to the phosphorescence spectrum of the dopant material was observed from this light-emitting element, and high-intensity green light emission with favorable color purity was obtained. The durability was evaluated at a DC drive of 20 mA / square centimeter for 100 hours. Even after that, high-brightness green light emission with good color purity was obtained.

Example 6 4,4′-bis (N-carbazolyl) biphenyl (CBP: molecular weight 484) was used as the host material of the light emitting material, and 2,2 ′, 7,7′-tetrakis (as the electron transport material. 2,2-diphenylvinyl) spiro-9,9'-
A light emitting device was produced in exactly the same manner as in Example 1 except that bifluorene (molecular weight 1029) was used. An emission spectrum similar to the phosphorescence spectrum of the dopant material was observed from this light-emitting element, and high-intensity green light emission with favorable color purity was obtained. The durability was evaluated at a DC drive of 20 mA / square centimeter for 100 hours. Even after that, high-brightness green light emission with good color purity was obtained.

Example 7 Same as Example 4 except that 2,2′-bis (2,2-diphenylethen-1-yl) spiro-9,9′-bifluorene (molecular weight: 673) was used as the electron transport material. Then, a light emitting device was produced. An emission spectrum similar to the phosphorescence spectrum of the dopant material was observed from this light-emitting device, and high-luminance green emission with favorable color purity was obtained.

Example 8 Bis {2- (2-benzothiophenyl) pyridyl} (acetylacetonate) as a dopant material for a light emitting material
A light emitting device was produced in exactly the same manner as in Example 1 except that the iridium complex was used. An emission spectrum similar to the phosphorescence spectrum of the dopant material was observed from this light emitting device, and high-luminance red light emission with good color purity was obtained.
When the durability was evaluated by direct current drive of mA / square centimeter, high-luminance red light emission with good color purity was obtained even after 100 hours.

Example 9 A glass substrate (manufactured by Asahi Glass Co., Ltd., 15Ω / □, electron beam method) on which an ITO transparent conductive film was deposited to a thickness of 150 nm was cut into 30 × 40 mm, and a 300 μm pitch (remaining width was obtained by a photolithography method. 270 μm) × 32 stripes were patterned. In order to facilitate electrical connection to the outside, one side of the ITO stripe in the long side direction is 1.
It is widened to a pitch of 27 mm (opening width 800 μm). The obtained substrate was ultrasonically cleaned for 15 minutes each with "Semicoclin 56" and ultrapure water, and then dried. This substrate was subjected to UV-ozone treatment for 1 hour immediately before producing a light emitting device,
Installed in a vacuum evaporation system, the degree of vacuum in the system is 5 x 10
^It was evacuated to ^-4 Pa or less. By the resistance heating method,
First, 4,4'-bis (N- (1-
Naphthyl) -N-phenylamino) biphenyl (αNP
D) was vapor-deposited at 60 nm. Next, 2,2'-bis (4- (N, N'-diphenylamino) phenyl) spiro-9,9'-bifluorene was used as the host material of the light emitting material, and the tris (2-phenylpyridyl) iridium complex was used as the dopant material. (Ir (ppy) ₃ ) was used to co-evaporate to a thickness of 30 nm so that the dopant was 8 wt%. Next, as a hole blocking layer, 2,9-dimethyl-4,7-
Diphenyl-1,10-phenanthroline (BTCP
N) was deposited by 10 nm. Next, as an electron-transporting material,
50n of tris (8-quinolinol) aluminum complex
It was vapor-deposited to a thickness of m. Next, a mask provided with 16 250 μm openings (remaining width 50 μm, corresponding to 300 μm pitch) on a Kovar plate having a thickness of 50 μm by wet etching was exchanged with the mask in a vacuum so as to be orthogonal to the ITO stripes. It was fixed with a magnet from the back so that the ITO substrate and the ITO substrate were in close contact. And 0.5 nm of lithium
200 nm of aluminum after doping the organic layer
A 32 × 16 dot matrix device was produced by vapor deposition.
When this device was matrix-driven, characters could be displayed without crosstalk.

[0073]

The light emitting device of the present invention has high luminous efficiency,
It has high brightness, excellent color purity, and improved durability.

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Claims (5)

[Claims] 1. An element which has a luminescent substance between an anode and a cathode and emits light by electric energy, and which contains a sublimable organic material having a molecular weight of 600 or more and a triplet luminescent material. A light emitting element characterized by. 2. The organic material according to the following general formula (1)
At least one selected from the group consisting of the compounds represented by (5)
A light-emitting element characterized by being a kind of both. [Chemical 1] (Where R¹~ R^TenAre the same or different
Also, hydrogen, alkyl group, aryl group, alkoxy
Group, condensed aromatic carbonization formed between adjacent substituents
It is selected from hydrogen ring structures. X¹Is a single bond, alkyl chain,
Cycloalkyl chain, alkylene chain, aryl chain, heterocycle
Chain, silyl chain, ether chain, thioether chain
More individually or in combination. n is 2
Represents the above natural numbers. ) [Chemical 2] (Where R¹¹Is selected from hydrogen, alkyl and aryl groups
Be done. n represents a natural number of 4 or more. ) [Chemical 3] (Where R¹²~ R^{twenty one}Are the same or different
Also, hydrogen, alkyl group, aryl group, alkoxy
Group, condensed aromatic carbonization formed between adjacent substituents
It is selected from hydrogen ring structures. Also, R¹⁶-R¹⁷The spaces are connected
It may be. X ²Is a single bond, alkyl chain,
Alkyl chain, alkylene chain, aryl chain, heterocyclic chain, silyl
Single chain from any of the following chains: ether chain, ether chain, thioether chain
Or selected from a combination. n is 2 or more
Represents a natural number. ) [Chemical 4] (Where R^{twenty two}~ R²⁹Are the same or different
Also, hydrogen, alkyl group, aryl group, alkoxy group
Chosen from. However, R^{twenty two}~ R²⁹One of them is X ³With
Used for joining. X³Is a single bond, alkyl chain,
Alkyl chain, alkylene chain, aryl chain, heterocyclic chain, silyl
Single chain from any of the following chains: ether chain, ether chain, thioether chain
Or selected from a combination. n is 2 or more
Represents a natural number. ) [Chemical 5] (Where R³⁰Is a substituent that can be modified at any position
From hydrogen, alkyl groups, aryl groups, and alkoxy groups
To be elected. X^FourIs a single bond, alkyl chain, cycloalkyl
Chain, alkylene chain, aryl chain, heterocyclic chain, silyl chain,
Alone or from either ether chain or thioether chain
Selected from a combination. Y is oxygen or nitrogen
Hydrogen, alkyl group, aryl in the case of nitrogen
Any of the groups are modified. n is a natural number of 2 or more
You ) 3. The light emitting device according to claim 1, wherein the triplet light emitting material is an iridium complex or a platinum complex. 4. The light emitting device according to claim 1, wherein the organic material and the triplet light emitting material are contained in the same layer. 5. The light emitting device according to claim 1, which is a display for displaying by a matrix and / or segment system.